12.4.Â Device Hints

Contributed by TomRhodes.

During initial system startup, the boot loader(8) reads
device.hints(5). This file stores kernel boot information
known as variables, sometimes referred to as
“device hints”. These “device hints”
are used by device drivers for device configuration.

Device hints may also be specified at the Stage 3 boot
loader prompt, as demonstrated in SectionÂ 12.2.3, “Stage Three”.
Variables can be added using set, removed
with unset, and viewed
show. Variables set in
/boot/device.hints can also be overridden.
Device hints entered at the boot loader are not permanent and
will not be applied on the next reboot.

Once the system is booted, kenv(1) can be used to dump
all of the variables.

The syntax for /boot/device.hints
is one variable per line, using the hash
“#” as comment markers. Lines are constructed as
follows:

hint.driver.unit.keyword="value"

The syntax for the Stage 3 boot loader is:

set hint.driver.unit.keyword=value

where driver is the device driver name,
unit is the device driver unit number, and
keyword is the hint keyword. The keyword may
consist of the following options: